JP2005292503A - Organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display which uses self-emitting organic EL elements arranged in a matrix to display, and can reduce uneven luminance between the pixels in a simple configuration with less sacrificing the aperture ratio. <P>SOLUTION: The display has a light emitting part; a current control part to control the current to the light emitters; a photoelectric converter part to detect the light from the light emittiers ant generate current; a 1st switching part to switch transmitting/non-transmitting of the generated current; an amplifier part to convert the current from the 1st switch to a voltage and amplify; a comparator amplifier part to compare and amplify the voltage from the amplifier and the voltage matching the image sign; a 2nd switching part to switch transmitting/non-transmitting of the voltage obtained by comparing and amplifying; and an image signal storage capacitor to store the image signals charged or discharged by the voltage from the 2nd switch. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL display device that performs display by using self-emitting organic EL (electroluminescence) elements in pixels and arranging them in a matrix, and is particularly suitable for reducing luminance variation for each pixel. The present invention relates to an organic EL display device.

  A display device using an organic EL element has a feature that an LCD (Liquid Crystal Display) does not have a backlight because the organic EL element is a self-light-emitting element and does not require a backlight. In addition, since it has characteristics of a high-speed response and a wide viewing angle, and since the element itself is solid, it has any advantages that can be applied to flexible applications.

  As a driving method of the organic EL display device, PM (passive matrix) driving and AM (active matrix) driving can be performed in the same manner as the LCD. However, a thin film transistor (TFT) is provided for each pixel to control the pixel individually. The AM method has become mainstream. As a result, higher definition, longer life, and further lower power consumption are considered.

  By the way, in order to control the light emission of each pixel of the organic EL display device without variation, it is necessary to align the current values of each pixel with respect to a certain image signal. In particular, this is important in the case of a method in which an image signal is given as an analog signal and the pixel emits light in accordance with the analog value. Examples of display devices aimed at reducing luminance unevenness include those disclosed in Patent Documents 1 and 2 below.

The organic EL display device disclosed in Patent Document 1 uses a configuration in which negative feedback is performed so that a pixel current matches an image signal. As a result, even if there is a variation in the characteristics of the input voltage versus the output current of the current control circuit, this is absorbed and a current value that is uniform between pixels for a certain image signal is obtained. The display device of Patent Document 2 discloses a configuration in which light emitted from a light emitting unit is detected by a photodiode and fed back to an image signal. It is considered that almost the same effect can be obtained by this.
JP 2002-91377 A JP 2003-271098 A

  However, the configuration disclosed in Patent Document 1 inevitably requires an error amplifying circuit necessary for negative feedback to be formed for each pixel, so that the display aperture ratio (the ratio of the net light emitting area to the display area) is increased. This is considered disadvantageous. The configuration disclosed in Patent Document 2 is considered to require a reset circuit and a reset signal path in order to obtain the feedback signal, and the configuration complexity cannot be avoided.

  The present invention has been made in consideration of the above circumstances, and in an organic EL display device that performs display by using organic EL elements that self-emit light in pixels and arranging them in a matrix, each pixel has a simple configuration. An object of the present invention is to provide an organic EL display device which can reduce the variation in luminance and reduce the sacrifice of the aperture ratio.

  In order to solve the above problems, in the organic EL display device according to the present invention, a plurality of pixels are arranged in a matrix, a pixel is selected from the plurality of pixels according to a pixel selection signal, and the selected pixel is An organic EL display device that emits light according to an image signal, a light-emitting unit, a current control unit that controls a current that flows through the light-emitting unit, and a photoelectric conversion unit that detects a light emitted from the light-emitting unit and generates a current A first switching unit that switches between transmission / non-transmission of the generated current according to the pixel selection signal, and amplification that amplifies the current transmitted from the first switching unit by current-voltage conversion And a comparison amplification unit that compares and amplifies a voltage value obtained by the amplification and a voltage value corresponding to the image signal, and the comparison amplification result according to the pixel selection signal. A second switching unit that switches between transmission and non-transmission of a pressure value, and an image signal holding capacitor that is charged and discharged by the voltage value transmitted from the second switching unit, and the current control The unit controls the current that flows through the light emitting unit according to a charging voltage of the image signal holding capacitor.

  In this configuration, the image signal is input to one of the comparison amplification units, and the other input is obtained by current-voltage conversion amplification of the current generated by the photoelectric conversion unit via the first switching unit. Voltage is given. The output of the comparison amplification unit is supplied to the image signal holding capacitor and the current control unit via the second switching unit. In such a configuration, it is easily achieved that the first switching unit of each pixel is used for the multiplexer and the second switching unit of each pixel is used for the demultiplexer. That is, since only one comparison amplification unit is required for a plurality of pixels, it is not necessary to provide a comparison amplification unit for each pixel. Therefore, a factor that decreases the aperture ratio can be eliminated. Moreover, since negative feedback is performed by the comparison amplification unit from the light emitting unit through the photoelectric conversion unit and the amplification unit, even if there is a variation in the characteristics of the input voltage versus the output current of the current control unit, this is absorbed and fixed. A current value that is aligned between pixels with respect to the image signal is obtained.

  The organic EL display device according to the present invention has a comparison amplification unit for negative feedback, but this comparison amplification unit is not provided for each pixel, and a reset circuit is not required, and the configuration is simple. It is possible to reduce luminance variation for each pixel and reduce the sacrifice in terms of aperture ratio.

  As an embodiment of the present invention, the light emitting unit and the photoelectric conversion unit include a common layer that performs light emission and photoelectric conversion, and a common cathode electrode that is stacked on one side of the common layer. The light emitting unit further includes a light emitting unit anode electrode formed on a side different from the one side of the common layer, and the photoelectric conversion unit is defined as the one side of the common layer. The photoelectric conversion unit anode electrode may further include a photoelectric conversion unit anode electrode formed on a different side and adjacent to the light emitting unit anode electrode. It is an example which takes the structural consistency with formation of a photoelectric conversion part when a light emission part is formed on the ground reference. According to this, the structure which implement | achieves the optical coupling of a light emission part and a photoelectric conversion part for every pixel is obtained easily.

  Further, as an embodiment, the light emitting unit, the current control unit, the photoelectric conversion unit, the first switching unit, the second switching unit, and the image signal holding capacitor are provided for each of the plurality of pixels. And there is one amplification unit and one comparison amplification unit for each column of pixels in the matrix, and the connection from the first switching unit to the amplification unit is connected to the column of pixels to which the comparison amplification unit belongs. It can be said that all the pixels included are connected, and the connection from the comparison amplification unit to the second switching unit is made for all the pixels included in the column of pixels to which the comparison amplification unit belongs. .

  This is a configuration in which the use of the first and second switching units described above as multiplexers or demultiplexers is summarized for each column of matrix pixels. According to this, only one amplifying unit and comparative amplifying unit are required for each column, and the number of amplifying units and comparative amplifiers to be built can be minimized.

  Further, as an embodiment, the current control unit is an n-channel thin film transistor, outputs the current flowing through the light emitting unit as a drain-source current, and the image signal holding capacitor supplied with the control of the current to the gate It can be set as the structure made by the charging voltage of. In this configuration, an n-channel thin film transistor is used for the current control unit.

  As an embodiment, the current control unit is a p-channel thin film transistor, outputs the current flowing through the light emitting unit as a source / drain current, and the image signal holding capacitor supplied with the control of the current to the gate It is also possible to adopt a configuration in which the charging voltage is made by the following charging voltage. In this configuration, a p-channel thin film transistor is used for the current control unit.

  Based on the above, embodiments of the present invention will be described below with reference to the drawings. First, prior to the description of the embodiment, the cause of luminance unevenness in each pixel in the organic EL display device will be described with reference to FIG. FIG. 7 is an equivalent circuit diagram illustrating a configuration of each pixel of an organic EL display device as a comparative example. FIG. 7A shows a configuration using p-channel transistors 56 and 58 as thin film transistors (TFT), and FIG. 7B shows a configuration using n-channel transistors 56a and 58a as thin film transistors.

  In the case shown in FIG. 7A, the organic EL element 54 that is a light emitting portion is formed with reference to the ground, and in the case shown in FIG. 7B, the organic EL element 54a is formed with reference to the power source. Reference numerals 57 and 57a denote image signal holding capacitors, reference numeral 51 denotes a power supply line, reference numeral 52 denotes an image signal line, and reference numeral 53 denotes a scanning line. Although not shown, the image signal line 52 is commonly connected to other pixels in the vertical (column) direction, and the scanning line 53 is commonly connected to other pixels in the horizontal (row) direction.

  An image signal is supplied to the image signal line 52 with an analog value (voltage), and a pixel selection signal is supplied to the scanning line 53 in synchronization therewith. When the pixel selection signal is supplied to the scanning line 53, the transistor 58 (58a) is turned on to charge and discharge the image signal holding capacitor 57 (57a) according to the voltage of the image signal on the image signal line 52. Capacitor 57 (57a) then holds that voltage until transistor 58 (58a) becomes conductive. The transistor 56 (56a) controls its drain current by the voltage held in the capacitor 57 (57a).

Here, the input voltage (gate-source voltage Vgs) of the transistor 56 (56a) versus the output current (drain current Ids, particularly in the case of the p-channel transistor 56, the source / drain current, the n-channel transistor 56a The case is also referred to as a drain-source current). That is, Ids = (1/2) · μ · Cox · (W / L) · (Vgs−Vth) ² . Here, μ is the carrier mobility, Cox is the gate capacity per unit area, W is the channel width, L is the channel length, and Vth is the threshold voltage. As can be seen from this equation, when the threshold voltage Vth varies from pixel to pixel, the output current (drain current Ids) varies in a square characteristic (that is, very sensitive) with respect to the same input voltage (gate-source voltage Vgs). Understand. The drain current Ids is a current that flows through the organic EL element 54 (54a) as it is, resulting in a current variation, that is, a luminance variation.

  For the TFT as the transistor 56 (56a), polycrystalline silicon having an excellent current driving capability is often used as the channel material. However, the threshold voltage Vth varies depending on the characteristics of the device, for example, about several tens of mV. . Therefore, in the configurations of these comparative examples, luminance variations for each pixel as a display device cannot be avoided. In addition, it is not preferable to employ a design in which the center value of Vth is reduced in order to reduce the variation in the drain current Ids, because the drain current Ids increases and the power consumption cannot be reduced as an organic EL display device.

  On the other hand, FIG. 1 is a block diagram showing a configuration of a specific pixel in the organic EL display device according to the embodiment of the present invention. As shown in FIG. 1, a power line 1, an image signal line 2, and a scanning line 3 are connected to this pixel, and a light emitting unit 4, a photoelectric conversion unit 5, a current control unit 6, and an image signal holding capacitor 7. , First switching unit 8, second switching unit 9, comparison amplification unit 10, operational amplification circuit 15, and resistor 16. The light emitting unit 4 and the photoelectric conversion unit 5 are optically coupled and function as the optical coupling unit 40. The operational amplifier circuit 15 and the resistor 16 function as a current input type amplifier circuit (amplifier). Although not shown, the scanning line 3 is commonly connected to other pixels in the horizontal (row) direction.

  The light emitting unit 4 is an organic EL element formed on the basis of the ground, and its anode side is connected to the current output terminal of the current control unit 6. The current control unit 6 controls the current flowing through the light emitting unit 4, and the control input terminal is connected to one end of the capacitor 7 so that the control follows the voltage held by the voltage holding capacitor 7. The photoelectric conversion unit 5 is connected between the ground and one end of the first switching unit 8, detects the light of the light emitting unit 4 that emits light by the current as a result of being controlled by the current control unit 6, and detects the photoelectric according to the light amount. A current is generated by conversion. The generated current is guided to a current input type amplifier circuit (comprising an operational amplifier circuit 16 and a resistor 16) through the first switching unit 8.

  The first switching unit 8 is provided between the photoelectric conversion unit 5 and the inverting input terminal of the operational amplifier circuit 15, and switches between transmission and non-transmission based on a pixel selection signal from the scanning line 3, and photoelectric conversion is performed during transmission. The current generated in the unit 5 is guided to the inverting input terminal of the operational amplifier circuit 15. The second switching unit 9 is provided between the output of the comparison amplification unit 10 and one end of the image signal holding capacitor 7 and the control input terminal of the current control unit 6, and transmits / receives based on the pixel selection signal from the scanning line 3. The non-transmission is switched, and the output voltage of the comparison amplification unit 10 is guided to one end of the image signal holding capacitor 7 and the control input terminal of the current control unit 6 during transmission.

  The operational amplifier circuit 15 constitutes an amplifying unit together with the resistor 16, and a constant voltage (for example, −5 V) is applied to the non-inverting input terminal, and the inverting input terminal is connected to the photoelectric converter via the first switching unit 8. The current generated by the converter 5 is guided as an input current. A resistor 16 is connected between the output terminal and the inverting input terminal of the operational amplifier circuit 15, thereby generating a voltage after a predetermined current voltage amplification at the output terminal of the operational amplifier circuit 15. The generated output voltage is guided to the non-inverting input terminal of the comparison amplification unit 10.

  The comparison amplification unit 10 has a function of subtracting the voltage of the inverting input terminal from the voltage of the non-inverting input terminal, amplifying the result with a large gain, and outputting the result, and the inverting input terminal has the operational amplifier circuit 15 as described above. The output terminal is connected to the second switching unit 9 as described above, and the image signal from the image signal line 2 is supplied to the non-inverting input terminal. Note that a broken line 2B drawn so as to join the inverting input terminal of the operational amplifier circuit 15, a broken line 2A drawn extending from the output of the comparison amplifier 10, and a long broken line 20 drawn extended to the image signal line 2 It will be described later.

  According to the pixel of the organic EL display device having the configuration shown in FIG. 1, an image signal is given to the image signal line 2, and a pixel selection signal is given to the scanning line 3, so that the first and second switching units 8, 9 In the closed state, a voltage substantially equal to the image signal becomes the output voltage of the operational amplifier circuit 15. This is negative in the loop of the photoelectric conversion unit 5, the first switching unit 8, the amplification unit (the operational amplification circuit 15 and the resistor 16), the comparison amplification unit 10, the second switching unit 9, the current control unit 6, and the photoelectric conversion unit 5. This is because a feedback path is formed and the relationship between the non-inverting input and the inverting input of the comparison amplification unit 10 is in a so-called imaginary short state.

  Therefore, the generated current in the photoelectric conversion unit 5 is a value corresponding to the image signal given to the image signal line 2, and the generated current is based on the amount of light detected by the light emitting unit 4. The amount of light emitted by the light emitting unit 4 is a value corresponding to the image signal given to the image signal line 2. In other words, if photoelectric conversion in the optical coupling unit 40 composed of the light emitting unit 4 and the photoelectric conversion unit 4 is regarded as detection through the light of the current flowing through the light emitting unit 4, variation in the current flowing through the light emitting unit 4 due to negative feedback. It can be said that the principle is lost. Therefore, there is no luminance variation for each pixel. The image signal holding capacitor 7 generates a voltage that makes the current value of the light emitting unit 4 constant regardless of variations in characteristics of the input voltage versus the output current of the current control unit 6 due to the negative feedback path.

  As a display device, it is the easiest configuration to arrange such pixel configurations in the vertical (column) and horizontal (row) directions. In this case, the image signal line 2 is provided so as to extend like a long broken line 20 and be connected in common to other pixels in the vertical (column) direction. No conducting wire corresponding to the broken lines 2A and 2B is provided. However, in this case, since it is necessary to provide the comparison amplification unit 10, the operational amplification circuit 15, and the resistor 16 in addition to the first and second switching units 8 and 9 for each pixel, the aperture ratio (display area) This is disadvantageous in terms of the ratio of the net light-emitting portion area to.

  Therefore, a configuration in which the comparison amplification unit 10, the operational amplification circuit 15, and the resistor 16 do not need to be provided in each pixel is also conceivable. It is provided with a broken line 2B drawn so as to merge with the inverting input terminal of the operational amplifier circuit 15 and a broken line 2A drawn extended from the output of the comparison amplifier 10 as conductive lines, and these conductive lines are provided for each pixel in the column direction. Connect in common. No conducting wire corresponding to the long broken line 20 is provided. In each pixel (not shown) to which the broken lines 2B and 2A are connected, the comparison amplification unit 10, the operational amplification circuit 15, and the resistor 16 are not provided.

  In this configuration, that is, the first switching unit 8 becomes a multiplexer that selects the output of the photoelectric conversion unit 5 of each pixel in the column direction, and the second switching unit 9 goes to the image signal holding capacitor 7 of each pixel in the column direction. The demultiplexer distributes the output of the comparison amplification unit 10. These selection and distribution are performed by a pixel selection signal given to the scanning line 3. According to such a configuration, at least one comparison amplifier 10, an operational amplifier circuit 15, and a resistor 16 are sufficient for each column, and it is not necessary to build in a display surface as a display device. A big effect is acquired. A configuration in which one pixel is provided for each pixel in a plurality of rows in each column instead of one in each column may be employed.

  Note that the amplifying unit by the operational amplifier circuit 15 and the resistor 16 is a current-voltage conversion type amplifier. In short, it only needs to have a function of amplifying a weak current generated by the photoelectric conversion unit 5 with a voltage value output. A configuration other than the use of such an operational amplifier circuit may be employed. For example, a simple configuration in which a current generated by the photoelectric conversion unit 5 is supplied to a resistor having one end connected to a constant voltage via the first switching unit 8 and the voltage generated at the other end of the resistor is used as an output voltage is also possible. possible. However, it should be noted that the resistance value increases to ensure sufficient amplification, and the influence of parasitic capacitance may not be negligible. When such parasitic capacitance occurs, the frequency characteristics of the circuit deteriorate and a desired operation speed cannot be obtained.

  FIG. 2 is a cross-sectional view schematically showing a configuration of the optical coupling unit 40 including the light emitting unit 4 and the photoelectric conversion unit 5 shown in FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 2, the light emitting unit 4 and the photoelectric conversion unit 5 can be formed adjacent to each other on the same glass substrate 41.

  The light emitting unit 4 includes a light emitting unit anode electrode 42 formed in a layer on a glass substrate 41, an organic EL layer 44 formed on the light emitting unit anode electrode 42, and a common cathode electrode formed on the organic EL layer 44. 45. The photoelectric conversion unit 5 includes a photoelectric conversion unit anode electrode 43 formed on the glass substrate 41, an organic EL layer 44 formed on the photoelectric conversion unit anode electrode 43, and a stack on the organic EL layer 44. The common cathode electrode 45 is formed. That is, the light emitting unit 4 and the photoelectric conversion unit 5 are different from each other only in the anode electrode, and the other glass substrate 41, the organic EL layer 44, and the common cathode electrode 45 are common, and the configuration is extremely consistent. . As can be seen from FIG. 1, a ground level voltage is applied to the common cathode electrode 45.

  As shown in the drawing, a part of the light emitted from the light emitting unit 4 travels in the direction of the glass substrate 41, and this becomes direct light emission as a display device. On the other hand, the other part proceeds in the layer direction in the organic EL layer 44 and is received and detected by the organic EL layer 44 of the photoelectric conversion unit 5. In general, it is known that the latter is larger in the proportion of light emitted from the light emitting section 4 in the direction of the glass substrate 41 and the proportion in the organic EL layer 44 in the layer direction. In FIG. 2, the planar area of the light emitting unit 4 and that of the photoelectric conversion unit 5 are shown to be approximately the same, but in practice, the photoelectric conversion unit 5 is made smaller in consideration of the aperture ratio. You can do it.

  As shown in FIG. 2, the light emitting unit 4 and the photoelectric conversion unit 5 can be formed in a configuration in which optical coupling is extremely tight. In other words, the photoelectric conversion unit 5 can have a function of detecting the current flowing through the light emitting unit 4 through light with high accuracy.

  FIG. 3 is a circuit diagram showing an example in which specific elements are applied to each block in the embodiment shown as a block diagram in FIG. 3, the same reference numerals are given to the same components as those in FIG. In this example, n-channel transistors 6 a, 8 a, and 9 a are used for the current control unit 6, the first switching unit 8, and the second switching unit 9, respectively. As is well known, the transistors 6a, 8a and 9a can be thin film MOS transistors formed on a glass substrate. In particular, the transistor can be made of amorphous silicon.

  Supplementing the connection of the n-channel transistors 6a, 8a, 9a is as follows. The transistor 6 a has a source connected to the anode of the light emitting unit 4 and a drain connected to the power supply line 1. The gate is connected to one end of the image signal holding capacitor 7. The transistor 8 a has a gate connected to the scanning line 3, a drain connected to one end of the photoelectric conversion unit 5, and a source connected to the inverting input terminal of the operational amplifier circuit 15. The transistor 9 a has a gate connected to the scanning line 3, a drain connected to the output of the comparison amplifier 10, and a source connected to one end of the image signal holding capacitor 7. Since the transistors 8a and 9a perform switching operation, the source and drain can be reversed.

  FIG. 4 is a block diagram showing the configuration of a specific pixel in an organic EL display device according to another embodiment of the present invention. Components identical to those already described in FIG. 4 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, unlike the embodiment shown in FIG. 1, the other end of the image signal holding capacitor 7a is connected to the power line 1 instead of the ground. There is no difference in operation as a pixel due to the difference between the capacitor 7 and the capacitor 7a.

  FIG. 5 is a circuit diagram showing an example in which specific elements are applied to each block in the embodiment shown as a block diagram in FIG. In FIG. 5, the same reference numerals are given to the same components as in FIG. In this example, p-channel transistors 6b, 8b, and 9b are used for the current control unit 6, the first switching unit 8, and the second switching unit 9, respectively. As is well known, the transistors 6b, 8b, 9b can be thin film MOS transistors formed on a glass substrate. In particular, the transistor can be made of amorphous silicon.

  Supplementing the connection of the p-channel transistors 6b, 8b, and 9b is as follows. The transistor 6 b has a drain connected to the anode of the light emitting unit 4 and a source connected to the power supply line 1. The gate is connected to one end of the image signal holding capacitor 7a. The transistor 8 b has a gate connected to the scanning line 3, a source connected to one end of the photoelectric conversion unit 5, and a drain connected to the inverting input terminal of the operational amplifier circuit 15. The transistor 9b has a gate connected to the scanning line 3, a source connected to the output of the comparison amplifier 10, and a drain connected to one end of the image signal holding capacitor 7a. Since the transistors 8b and 9b are for switching operation, the source and drain can be reversed.

  FIG. 6 is a repetition of what has already been described. However, when the pixels having the configuration shown in FIG. 1 are used to arrange the pixels vertically and horizontally, the power line 1, the image signal line 2, the scanning line 3, and each pixel are arranged. It is a figure which shows a connection. In FIG. 6, the components already described are given the same numbers. As shown in FIG. 6, the pixels 11, 12,... Are arranged in the horizontal (row) direction, and the pixels 11, 21,. From this figure, it can be easily understood that the comparison amplifier 10, the operational amplifier circuit 15, and the resistor 16 are not required for each pixel.

1 is a block diagram showing a configuration of a specific pixel in an organic EL display device according to an embodiment of the present invention. Sectional drawing which shows typically the structure of the light emission part and photoelectric conversion part which were shown in FIG. The circuit diagram which shows the example which applied the specific element to each block in embodiment shown as a block diagram in FIG. The block diagram which shows the structure of the specific pixel in the organic electroluminescence display which concerns on another embodiment of this invention. The circuit diagram which shows the example which applied the specific element to each block in embodiment shown as a block diagram in FIG. FIG. 3 is a diagram showing connections between a power supply line 1, an image signal line 2, a scanning line 3 and each pixel when pixels are arranged vertically and horizontally using the pixels having the configuration shown in FIG. 1. The equivalent circuit diagram which shows the structure for every pixel of the organic electroluminescence display as a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Power supply line, 2 ... Image signal line, 3 ... Scanning line, 4 ... Light emission part, 5 ... Photoelectric conversion part, 6 ... Current control part, 6a ... N channel transistor, 6b ... P channel transistor, 7, 7a ... Image Signal holding capacitor, 8... First switching unit, 8a... N channel transistor, 8b... P channel transistor, 9... Second switching unit, 9a... N channel transistor, 9b. , 12, 21, 22 ... pixels, 15 ... operational amplifier circuit, 16 ... resistor, 40 ... optical coupling part, 41 ... glass substrate, 42 ... light emitting part anode electrode, 43 ... photoelectric conversion part anode electrode, 44 ... organic EL layer 45: Common cathode electrode.

Claims (6)

An organic EL display device in which a plurality of pixels are arranged in a matrix, a pixel is selected according to a pixel selection signal from the plurality of pixels, and the selected pixel is caused to emit light according to an image signal,
A light emitting unit;
A current control unit for controlling a current flowing through the light emitting unit;
A photoelectric conversion unit that detects light emitted from the light emitting unit and generates a current;
A first switching unit for switching transmission / non-transmission of the generated current according to the pixel selection signal;
An amplifying unit for converting the current transmitted from the first switching unit to current-voltage conversion and amplifying;
A comparison amplifier for comparing and amplifying the voltage value obtained by the amplification and the voltage value corresponding to the image signal;
A second switching unit that switches between transmission and non-transmission of a voltage value that is a result of the comparison amplification in accordance with the pixel selection signal;
An image signal holding capacitor that is charged and discharged by the voltage value transmitted from the second switching unit;
The organic EL display device, wherein the current control unit controls the current flowing through the light emitting unit by a charging voltage of the image signal holding capacitor. The light emitting unit and the photoelectric conversion unit have a common layer that performs light emission and photoelectric conversion, and a common cathode electrode that is stacked on one side of the common layer,
The light emitting unit further includes a light emitting unit anode electrode formed on a side different from the one side of the common layer,
The photoelectric conversion unit further includes a photoelectric conversion unit anode electrode formed on a side different from the one side of the common layer and adjacent to the light emitting unit anode electrode. Item 10. An organic EL display device according to Item 1. The light emitting unit, the current control unit, the photoelectric conversion unit, the first switching unit, the second switching unit, and the image signal holding capacitor are respectively provided in the plurality of pixels.
The amplification unit and the comparison amplification unit are provided one for each row of the matrix-like pixels,
The connection from the first switching unit to the amplifying unit is made from all the pixels included in the column of pixels to which the comparative amplifying unit belongs,
2. The organic EL display according to claim 1, wherein the connection from the comparison amplification unit to the second switching unit is made for all pixels included in a column of pixels to which the comparison amplification unit belongs. apparatus.   The current control unit is an n-channel thin film transistor, outputs the current flowing through the light emitting unit as a drain / source current, and the current is controlled by a charging voltage of the image signal holding capacitor supplied to the gate. The organic EL display device according to claim 1.   The current control unit is a p-channel thin film transistor, outputs the current flowing through the light emitting unit as a source / drain current, and the current is controlled by a charging voltage of the image signal holding capacitor supplied to the gate. The organic EL display device according to claim 1.   6. The organic EL display device according to claim 4, wherein the current control unit is an amorphous silicon thin film transistor.

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